Outline

Objective

HLA typing prior to transplantation of then HLA matched grafts has improved the clinical outcome in many settings of organ transplantation. In case of incompatibility in only minor histocompatibility antigens recipient-derived antigen presenting cells (APCs) need to pick up, process and present alloantigens to T-cells (indirect pathway) which should therefore result in a prolonged time of graft survival.

Methods

Four corneas of untreated C3H (H-2k) and DBA/2 (H-2d) mice were immunohistologically analysed for numbers of APCs in the most superficial subepithelial corneal layer. Corneal graft survival (n=6 each) in BALB/c (H-2d) mice was assessed for transplants obtained from the two different donor mouse strains: C3H or DBA/2. Immune responses were studied in proliferation assays using cells from the ipsilateral and contralateral submandibular lymph nodes of the recipients stimulated by irradiated donor spleen cells. IFN-gamma concentrations in cell culture supernatants were determined by ELISA. Two groups of recipients (n=8 each) were treated by ballistic gene transfer of CTLA-4 and IL-4 DNA to the skin of the left lower lid or to the left shank. (8 untreated controls).

Results

Corneae from both mouse strains contained similar numbers of F4/80+ cells (C3H: 29.5 Â± 6.1; DBA/2: 20.3 Â± 5.1; p=0.12). Allograft rejection occurred on day 14.5 Â± 4.1 with C3H and on day 25.0 Â± 5.6 with DBA/2 donor grafts (p=0.038). In proliferation assay considerable allogeneic T-cell proliferation was observed after transplantation of both C3H and DBA/2 donor corneas. Likewise, T-cells from draining lymph nodes secreted substantial amounts of IFN-gamma in both models. Allograft rejection occurred in 6 of 7 controls, in 7 of 8 shank-treated but only in 3 of the 7 lid-treated animals (p=0.026 vs. control, p=0.040 vs. treatment of shank).